Washington: The US government looks forward to working with Pakistan's newly-elected Prime Minister Raja Pervaiz Ashraf to bring the strained relations between the two countries back on track, the State Department has said.

"We are pleased that the leadership issue appears to have been settled," State Department spokeswoman Victoria Nuland told reporters at a news briefing on Friday.

"We obviously look forward to working with the new Prime Minister and hope that this will open space to continue to roll up our sleeves and get back on track with all of the things that we want to do with Pakistan," a news agency quoted her as saying.

Ashraf took oath of his office in Islamabad on Friday night at a ceremony administered by President Asif Ali Zardari, to replace Yousuf Raza Gilani, who was disqualified by the Supreme Court Tuesday over contempt of court.

The US-Pakistan relations have been soured since May 2011, when the US sent special forces into Pakistan to kill Al Qaeda mastermind Osama bin Laden, without noticing Islamabad in advance.

The ties took a turn for the worse in late November last year, when the US-led NATO forces in Afghanistan launched an air strike on Pakistan's border posts, killing 24 soldiers.

Pakistan closed NATO's land supply routes in retaliation and has been demanding for an apology from Washington for the incident. Past talks on reopening the routes have yielded no tangible results.

Nuland also said the US is very concerned about the connection between the Haqqani Network, a Taliban-affiliated group of militants, and the Thursday attack on a Kabul hotel that killed 23 people.

Nuland said the US hopes to have better cooperation with Pakistan on cracking down on the Haqqani Network. "This is at the core of this work we're trying to do to get past the differences we've had on counter